The present invention relates to a supporting disk for a supporting disk bearing arrangement for open-end spinning rotors which comprises a disk-shaped basic body made of plastic and an outer ring which is anchored to it, is also made of plastic, and whose circumference is constructed as a running surface for a shaft of an open-end spinning rotor, the outer circumference of the basic body and the inner circumference of the ring being provided with a surrounding undercut-type profiling respectively which engage in one another in a form-locking manner, and are developed as a projection on the ring and as a recess on the basic body. The invention also relates to a process for the manufacturing of such a supporting disk.
U.S. Pat. No. 4,893,946 shows the working into the circumference of a basic body a dovetailed groove in which the subsequently injection-molded-on plastic ring is anchored. The basic body is preferably made of aluminum but, according to Column 7, Lines 13-18 of U.S. Pat. No. 4,893,946, may also be made of plastic. Since the basic body is manufactured before the ring, the undercut situated in the basic body must be machined in a cutting manner. This not only represents additional manufacturing expenditures but also reduces the stability of the basic body at the critical point.
An object of the invention is to produce a supporting disk of the initially mentioned type in a low-cost manner and to anchor the ring securely on the basic body.
This and other objects are achieved in that the profiling is a non-cut profiling produced in a non-cutting manner.
This can be accomplished according to the present invention in that, contrary to the previous custom, the ring is not injection-molded to the basic body, but rather the basic body is injection-molded onto the ring. First, the ring is manufactured in a first tool as a component part; is taken out of this tool; and is then placed in a second tool in which the basic body (also made of plastic) is manufactured and is injection-molded onto the ring in the process. By such a process, it becomes possible to provide the profilings on the basic body and on the ring respectively in a non-cutting manner.
According to the present invention, it is therefore possible, despite the non-cutting manufacture, to also implement an undercut-type profiling if the profiling is not made on the ring but on the basic body as a recess. This results in the advantage that the whole thickness of the ring having the running surface is available for a damping of the open-end spinning rotor during the operation. The ring is therefore not weakened by recesses used for the anchoring.
Although they have been described in the literature, supporting disks whose basic body is made of plastic so far have not been used in series-produced machines. However, in contrast to basic bodies made of metal, basic bodies made of plastic have the advantage that the connection between the basic body and the ring becomes more intimate at the anchoring point because, in the case of a subsequent injection molding of the basic body to the ring, the surface of the ring is also heated at the contact point and is therefore softened.
Expediently, the profiling will be constructed to be approximately T-shaped in the axial sectional view, in which case the depth of the profiling may correspond approximately to the thickness of the ring. Furthermore, it is expedient for the interior circumference of the ring to have (in the axial sectional view) the same width as the outer circumference of the basic body. In this case, the width of the ring (in the axial sectional view) may correspond to approximately twice the thickness of the ring.
In an advantageous development of the invention, a narrow circumferential groove is worked into the ground running surface of the ring. Such circumferential grooves are used for the cooling of the running surface and have been successful in practice.
In certain embodiments of the invention, the basic body and the ring are made of different plastic materials. It is useful, for example, to manufacture the ring for reasons of damping from a more elastic plastic material than the basic body. While the ring should therefore be elastic but wear-resistant, the basic body is expediently made of a harder and firmer, preferably fiber-reinforced plastic material.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.